TWI420835B - Method, apparatus, and system for removal of modulated tonal interference - Google Patents

Description

Method, apparatus, and system for removing modulated tonal interference Field of invention

The present invention is generally directed to modulated tonal interference removal techniques.

Background of the invention

Wireless networks and wireless communications are quite popular in today's society. This has also created a need for enhanced functionality and faster and more reliable wireless communication technologies. The difficulty of wireless communication is caused by high-speed signals from, for example, but not limited to, a notebook personal computer (PC), which is caused by, for example, but not limited to, a wireless local area network (wireless LAN), a wireless wide area network. Road (WWAN), and/or interference embedded in, for example, wireless devices of other wireless networks in a mobile platform.

For example, a specific signal generated in a notebook computer has been found to be a source of severe radio frequency interference (RFI). In particular, timing signals for transmitting data to and from various portions of the PC (e.g., between a processor and a memory) have been found to be sources of electromagnetic interference (EMI).

Spread spectrum timing is a technique that reduces the average amplitude of clock harmonics by extending the energy at a fundamental clock frequency over a small frequency interval. While this technique is quite effective at reducing the interference of the radio receiver, it is still insufficient in many important situations, such as, for example, but not limited to, one of the small factor devices, the Global Positioning System (GPS).

The present invention has been mentioned that current tone suppression techniques such as tone deletion, nick filtering, and adaptation filtering assume that the tone interference signal has a fixed frequency or slowly changes over time. It does not utilize the known structure of the spread spectrum clock harmonics, and therefore does not require the removal of most of the signal energy close to the interfering signal.

This RFI problem due to clock harmonics has been described in U.S. Patent No. 7,279,989 issued to U.S. Pat. The patent uses a frequency adaptation procedure to reveal the slowdown of clock noise.

The management of the system clock for reducing RFI is disclosed in U.S. Patent Application Publication No. 2008/0081586, the entire disclosure of which is incorporated herein by reference. A frequency range of at least one active channel of the at least one wireless communication RF band can be identified, an overlap between the frequency range of the at least one active channel and the frequency range of the at least one clock harmonic can be identified, and The base frequency of one of the at least one clock is shifted to shift the frequency range of the at least one harmonic out of the frequency range of the at least one active channel.

An IEEE publication published by Wang Chensu and Moeness G. Amin (issued in the Journal of IEEE Signal Processing, No. 46, No. 1 in January 1998) is called "the performance analysis of instantaneous frequency interference cancellation technology in spread spectrum communication". In the case, it is revealed that the open loop adaptive filtering filter is used to slow down the direct sequence spread spectrum communication.

The present invention has identified a need to improve RFI inhibition.

According to an embodiment of the present invention, a method is specifically provided, comprising the steps of: determining a phase between a periodic extension signal and an effective extension signal of one of the modulation and interference harmonics; and estimating the interference harmonic One of the amplitudes; and eliminating the interfering harmonics from a received signal.

Simple illustration

The invention will be more fully understood from the following detailed description and the accompanying drawings. Description and understanding of the invention.

1A, 1B, and 1C are diagrams showing frequency versus time comparisons of certain embodiments of the present invention.

Figure 2 illustrates a system in accordance with some embodiments of the present invention.

Figure 3 illustrates a radio frequency interference (RFI) mitigation diagram for a spread spectrum clock harmonic in accordance with some embodiments of the present invention.

Detailed description of the preferred embodiment

Certain embodiments of the present invention relate to modulated tonal interference removal techniques.

In some embodiments, a phase between a periodic spread signal and an effective spread signal of one of the modulation and interference harmonics can be determined, and one of the interference harmonics can be estimated, and the interference harmonic can be Eliminated from a received signal (eg, a received communication signal). Other examples and patents are also described in this case.

In some embodiments, a phase estimator can determine a phase between a periodic spread signal and an effective spread signal of one of the modulation and interference harmonics, and an amplitude estimator can estimate one of the interference harmonics. The amplitude, and a pitch suppressor, cancel the interfering harmonics from a received signal.

In some embodiments, a system includes a computing platform, a radio transceiver coupled to the computing platform (and/or included in the computing platform), and an interference suppressor. The radio transceiver is used to transmit and receive radio frequency signals. The interference suppressor is used to track small fluctuations in the fundamental frequency of one or more clocks that interfere with the RF signals, and to eliminate or attenuate clock harmonic interference. The interference suppressor includes a phase estimator for determining a phase between a periodic spread signal and a modulated extension harmonic, and an amplitude estimator for estimating the interference harmonic An amplitude estimator and a tone suppressor that cancels the interfering harmonics from a received signal.

Spread spectrum timing is a technique that reduces the average amplitude of clock harmonics by extending the energy at a fundamental clock frequency over a small frequency interval. The current tone deletion algorithm treats the extended clock harmonics as a broadband interference signal rather than a one-time variable-band interference signal. Tonal breakdown can be used in accordance with certain embodiments that cut a portion of the spectrum. However, if a large amount of data is taken out, signal degradation occurs. According to some embodiments, there are fewer bit errors by taking a smaller portion of the spectrum. That is, according to some embodiments, tracking can be used to extract a smaller portion of the spectrum, resulting in fewer bit errors. In this mode, the extended clock harmonics are regarded as a one-time narrowing interference signal. This provides a more improved result than typical tone suppression techniques.

FIG. 1A illustrates a stretched clock harmonic spectrum diagram 100 in accordance with some embodiments. In the spectrum 100, the frequency is displayed on the vertical axis and the time is displayed on the horizontal axis. An interference spread harmonic amplification is displayed on the time axis. Since the frequency variation of the extension function is plotted in FIG. 1A using a triangular wave extension function. However, when the observation bandwidth is large, such as, for example, when using an orthogonal frequency division multiplexer (OFDM) receiver or a spectrum analyzer, the frequency variation cannot be observed and the energy appears to be in a small frequency interval. Spread on.

FIG. 1B illustrates how some methods currently use the spectrogram 110 to attempt to remove all of the energy in the band. In the spectrum 110, the frequency is displayed on the vertical axis and the time is displayed on the horizontal axis, and the size versus frequency diagram is shown in an exploded view in the graph 120 shown on the right side of FIG.

Figure 1B compares certain embodiments of the present invention in which only real time narrowing interfering signals are removed. In this manner, a very small amount of the information-bearing signal is removed with the interfering signal, resulting in fewer communication errors, higher throughput, and a larger range of wireless signals.

FIG. 1C depicts a stretched clock harmonic spectrum map 130 in accordance with some embodiments. In the spectrum 130, the frequency is displayed on the vertical axis and the time is displayed on the horizontal axis. The spectrum diagram 130 shows one of a reference clock harmonic extension function (a triangular wave shown by a solid line in FIG. 1C) and an effective extension function of a reception harmonic (a triangular wave indicated by a broken line in FIG. 1C) A phase delay between ).

FIG. 2 depicts a system 200 in accordance with some embodiments. The system 200 includes a clock generator 202, a small factor calculation platform 204 (such as but not limited to a notebook computer platform, a portable device platform, etc.), a digital spread spectrum reference signal 206, and a phase estimator 208. An amplitude estimator 210, a tone suppressor 212, a wireless wide area network (WWAN) baseband 214, a radio frequency (RF) front end 216, and/or a radio transceiver 218 (eg, including a transmitter and a receiver) One of the radio transceivers). In some embodiments, phase estimator 208 and amplitude estimator 210 are included and/or include an interference estimator and/or an interference tracker (e.g., in some embodiments that track a drift). In some embodiments, phase estimator 208, amplitude estimator 210, and/or tone suppressor 212 are included and/or include an interference suppressor. In some embodiments, the WWAN baseband 214 can be any radio baseband and/or any digital baseband and does not limit all embodiments to a WWAN baseband. In some embodiments, any or all of the elements of system 200 can be implemented in any combination of hardware and/or software.

System 200 tracks the small amount of variation in the fundamental frequency of the interfering clock to more effectively cancel or attenuate clock harmonic interference. In some embodiments, phase estimator 208 determines a phase difference between a signal comprising interference and a reference clock signal. In some embodiments, phase estimator 208 provides phase tracking and/or measurement. Phase estimator 208 determines the phase (e.g., the angular time difference) between a periodic spread signal and one of the modulated extension harmonics. This may be accomplished by direct measurement of the spread signal in accordance with certain embodiments (e.g., a wired connection between the clock generator 202 and the phase estimator 208, such as shown in Figure 2, by dashed lines is required). In some embodiments where a line segment between the clock generator and the phase estimator is not present, a reference signal can be generated. In some embodiments, phase estimator 208 determines the phase by using an artificially generated digital reference signal (e.g., from digital spread reference signal 206) coupled to the same phase locked loop. In some embodiments, phase estimator 208 demodulates the variable interference harmonics to recover, for example, one of the spreading functions, the delayed, delayed replica signal, and then estimates a delay. In some embodiments, phase estimator 208 uses an adapted minimum mean square error (MMSE) estimator to determine the phase. In some embodiments, the version of the spreading function (eg, sawtooth, triangle, sine, etc.) is known in advance and/or can be determined (eg, a portion of the MMSE estimate). In some embodiments, phase estimator 208 includes and/or includes a clock recovery circuit. In some embodiments, phase estimator 208 estimates the phase using any hardware and/or software implementation.

According to some embodiments, phase estimator 208 determines a phase between a periodic spread signal and one of the modulated extension harmonics. For example, according to some embodiments, the phase estimator 208 determines an effective spread of the periodic spread signal depicted by the solid line in FIG. 1C and the modulation-interference harmonic shown by the dashed line in the 1C diagram. This phase is shown in Figure 1C between the signals.

According to some embodiments, amplitude estimator 210 estimates the amplitude of the interfering harmonics. In some embodiments, this may be accomplished, for example, using an adaptive filter (e.g., a single tap adaptation filter in some embodiments), and/or using known spectral estimation techniques. In some embodiments, the amplitude can be estimated regardless of the phase. In some embodiments, the amplitude can be estimated along with the phase.

According to some embodiments, the tone suppressor 212 may cancel the interference harmonics from one of the received signals received via the radio transceiver 218 using a subtractive cancellation technique, an adaptive cancellation technique, and/or a time varying narrowband filtering technique.

In accordance with certain embodiments of the present invention (e.g., as depicted in FIG. 2 and described herein), only real time narrowing interfering signals are removed from the received signal. In this manner, a very small amount of the information-bearing signal is removed with the interfering signal, resulting in fewer communication errors, higher throughput, and a larger range of wireless signals.

Although only one clock generator is shown in FIG. 2, according to some embodiments of more than one clock generator, the clock signal and/or the reference signal may be included in one of the systems performing phase estimation (eg, such clock signals) And / or each of the reference signals). Although only one radio transceiver is shown in FIG. 2, in accordance with some embodiments, more than one radio transceiver may be included. Moreover, once the phase difference of a particular interfering harmonic is recovered, the phase difference of other interfering harmonics of other radio transceivers sharing the impact of a single RF front end can be easily calculated.

FIG. 3 illustrates a graphic 300 in accordance with some embodiments. The graph 300 plots the bit error ratio (BER) on the vertical axis and the noise ratio (Eb/No) on the horizontal axis. Graph 300 depicts the simulation results of RFI mitigation with spread spectrum clock harmonics of an Orthogonal Frequency Division Multiplexer (OFDM) communication system using quadrature phase shift keying (QPSK) modulation of uncoded data. The bit error ratio (BER) versus noise ratio (Eb/No) curve is plotted for common channel clock harmonic interference. The amplitude and phase estimation errors of the combination vary from 5% to 95%, and the curves are generated in accordance with certain embodiments. As shown in FIG. 3, the BER can be improved by a size equivalent to the second order compared to the state of the previous pitch breakdown method technique. This improvement is due to the fact that one of the signal energies has been removed at a lower level in accordance with certain embodiments.

According to certain embodiments, due to, for example, extending the radio range, achieving a minimum power of a given range, increasing throughput over a given range, and/or increasing coexistence at a given spatial location without interfering with each other With the number of wireless platforms, multi-radio computing platforms have improved performance over conventional systems. According to certain embodiments, radio frequency interference (RFI) has a lower impact on radio performance.

Although certain embodiments have been described herein as being performed in a particular manner, such specific implementations are not required in accordance with certain embodiments. For example, while certain embodiments have been described with reference to a triangular wave, it should be noted that some embodiments may refer to any other type of stretching function (eg, in some embodiments, a sine wave, a sawtooth wave, any other may be used) Type of waveform, etc.) to perform.

Although certain embodiments have been described with reference to specific embodiments, other embodiments are possible in accordance with certain embodiments. In addition, the arrangement and/or order of the circuit elements or other features illustrated in the drawings and/or illustrated herein are not to be construed in a particular manner. There may be many other arrangements in accordance with certain embodiments.

Each of the elements of the figures may have the same reference numerals or a different reference number in each of the illustrated embodiments to indicate that the representative elements may be different and/or identical. However, an element may be flexible enough to have different implementations and operate in conjunction with some or all of the elements of the systems shown or described herein. The various elements shown in the figures may be the same or different. One of the references is a first component and the second component is a free combination.

In the following description and claims, the terms "couple," and "connected," and their derivatives are used. It should be understood that the terms are not intended to be considered as synonyms. Instead, in particular embodiments, "Connected" may be used to mean that two or more elements are in direct contact with each other either physically or electrically. "Coupling" may mean that two or more elements are in direct physical or electrical contact. However, "coupled" can also mean two Or more components are not in direct contact with each other, but still operate or interact with each other.

One of the algorithms in this paper is generally considered to be a sequence of actions or operations that result in a desired result. These operations include entity manipulation of the number of entities. Usually, though not necessarily, the quantities are in the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. Sometimes the proof is convenient, and the signals are referred to as bits, values, elements, symbols, characters, items, numbers, etc., primarily for reasons of common use. However, it should be understood that all such and similar items are associated with the appropriate number of entities and that only those quantities of convenience are applied.

Some embodiments may be implemented in one or a combination of hardware, firmware, and software. Some embodiments may also be implemented as instructions stored on a machine readable medium, which may be read and executed by a computing platform to perform the operations described herein. A machine readable medium can include any mechanism for storing or transmitting information that can be read by a machine (eg, a computer). For example, a machine-readable medium can include read only memory (ROM); random access memory (RAM); disk storage media; optical storage media; cache memory devices; electrical, optical, acoustic, or other types. Propagating signals (eg, carrier waves, infrared signals, digital signals, interfaces for transmitting and/or receiving signals, etc.), as well as other signals.

An embodiment is an embodiment or example of the invention. Reference is made to the description of "an embodiment", "an embodiment", "an embodiment" or "an embodiment" or "an" At least some embodiments of the invention, but need not be included in all embodiments. The various embodiments of the various embodiments, "an embodiment", "an embodiment" or "an embodiment" are not necessarily referred to the same.

Not all of the components, features, architectures, characteristics, etc. described and illustrated herein are intended to be included in a particular embodiment or certain embodiments. For example, if the specification states that a component, feature, structure, or characteristic "may", "may", "can" or "may" be included, the particular component, feature, architecture, or characteristic may not be included . If the specification or the scope of the patent application is referred to as "a" or "an" element, it does not mean that there is only one element. If the specification or the scope of the patent application is referred to as "an additional" element, this does not exclude that there is more than one additional element.

Although the flowcharts and/or state diagrams may be used herein to illustrate the embodiments, the invention is not limited to the figures or the corresponding descriptions herein. For example, the process is not necessarily carried out in the exact same order as the illustrated blocks or states illustrated and described herein.

The invention is not limited to the specific details set forth herein. Indeed, those skilled in the art having the benefit of the present disclosure will recognize that many other variations of the foregoing description and drawings can be made in the scope of the invention. Accordingly, the following claims are intended to cover any modifications of the scope of the invention.

100, 130. . . Extended clock harmonic spectrum

110. . . Spectrum

120, 300. . . Graphics

200. . . system

202. . . Clock generator

204. . . Small factor computing platform

206. . . Digital spread spectrum reference signal

208. . . Phase estimator

210. . . Amplitude estimator

212. . . Tone suppressor

214. . . Wireless Wide Area Network (WWAN) baseband

216. . . Radio frequency (RF) front end

218. . . Radio transceiver

1A, 1B, and 1C are diagrams showing frequency versus time comparisons of certain embodiments of the present invention.

Figure 2 illustrates a system in accordance with some embodiments of the present invention.

Figure 3 illustrates a radio frequency interference (RFI) mitigation diagram for a spread spectrum clock harmonic in accordance with some embodiments of the present invention.

200‧‧‧ system

202‧‧‧clock generator

204‧‧‧Small factor computing platform

206‧‧‧Digital Spread Spectrum Reference Signal

208‧‧‧Phase estimator

210‧‧‧Amplitude estimator

212‧‧‧tone suppressor

214‧‧‧Wireless Wide Area Network (WWAN) baseband

216‧‧‧RF (RF) front end

218‧‧‧ radio transceiver

Claims (29)

A method for removing modulated tonal interference, comprising the steps of: determining a phase between a periodic spread signal and an effective spread signal of one of the modulation and interference harmonics; estimating the interference harmonic An amplitude; and canceling the interference harmonic from a received signal based on the phase and the amplitude. The method of claim 1, wherein the determining step is performed using direct measurement of the periodic spread signal. The method of claim 1, further comprising generating a digital reference signal, wherein the determining step is performed using the generated digital reference signal. The method of claim 1, further comprising estimating a mean square error, wherein the determining step is performed using the estimated mean square error. The method of claim 1, further comprising determining one of the periodic extension signals. The method of claim 1, wherein the estimating step and the determining step are performed independently of each other. The method of claim 1, wherein the estimating step is performed in conjunction with the determining step. The method of claim 1, wherein the eliminating step uses a subtractive cancellation technique, an adaptation cancellation technique, an adaptation filtering technique, and/or a time Variable narrowband filtering techniques are implemented to perform. The method of claim 1, wherein the eliminating step removes only a real time narrowing interference signal from the received signal. An apparatus for removing modulated tonal interference, comprising: a phase estimator for determining a phase between a periodic extension signal and an effective extension signal of a modulation-interference harmonic; An amplitude estimator for estimating an amplitude of one of the interference harmonics; and a tone suppressor for canceling the interference harmonic from a received signal based on the phase and the amplitude. The apparatus of claim 10, wherein the phase estimator is operative to determine the phase using a direct measurement of the periodic spread signal. The apparatus of claim 10, wherein the phase estimator is operative to further generate a digital reference signal and use the generated digital reference signal to determine the phase. The apparatus of claim 10, wherein the phase estimator is to further estimate a mean square error and use the estimated mean square error to determine the phase. The apparatus of claim 10, wherein the phase estimator is configured to further determine one of the periodic extension signals. The apparatus of claim 10, wherein the amplitude estimator is operative to estimate the amplitude independently of the phase estimator to determine the phase. The device of claim 10, wherein the amplitude estimator is used in conjunction with the phase estimator to estimate the amplitude to determine the phase. The device of claim 10, wherein the amplitude estimator is Adapt the filter. The device of claim 10, wherein the tone suppressor is used to use a subtractive cancellation technique, an adaptive cancellation technique, an adaptive filtering technique, and/or a time varying narrowband filtering technique. The apparatus of claim 10, wherein the tone suppressor is configured to remove only a real time narrowing interference signal from the received signal. A system for removing modulated tone interference, comprising: a computing platform; a radio transceiver coupled to the computing platform to transmit and receive radio frequency signals; and an interference suppressor for tracking interference a small amount of variation in the fundamental frequency of one or more clocks of the RF signal, and eliminating or attenuating clock harmonic interference, the interference suppressor comprising: determining a periodic spread signal and a modulation-interference harmonic a phase estimator of one phase between the effective extension signals; an amplitude estimator for estimating an amplitude of the interference harmonic; and means for canceling the interference harmonic from the received signal based on the phase and the amplitude One of the wave tone suppressors. A system as claimed in claim 20, wherein the phase estimator is operative to determine the phase using a direct measurement of the periodic spread signal. A system as claimed in claim 20, wherein the phase estimator is operative to further generate a digital reference signal and use the generated digital reference signal to determine the phase. Such as the system of claim 20, wherein the phase estimator is used The phase is determined by further estimating a mean square error and using the mean squared error of the estimate. The system of claim 20, wherein the phase estimator is configured to further determine one of the periodic stretch signals. A system of claim 20, wherein the amplitude estimator is operative to estimate the amplitude independently of the phase estimator to determine the phase. A system of claim 20, wherein the amplitude estimator is operative to combine the phase estimator to estimate the amplitude to determine the phase. The system of claim 20, wherein the amplitude estimator is an adaptive filter. The system of claim 20, wherein the tone suppressor is used to use a subtractive cancellation technique, an adaptive cancellation technique, an adaptive filtering technique, and/or a time varying narrowband filtering technique. The system of claim 20, wherein the tone suppressor is configured to remove only one real time narrowing interference signal from the received signal.